One Christmas, a parent decreed that she was no longer going to remind her children of their thank-you note duties.As a result their grandmother never received acknowledgments of the generous checks she had given.The next year things were different, however."The children came over in person to thank me," the grandparent told a friend triumphantly."How wonderful!" the friend exclaimed. "What do you think caused the change in behavior?""Oh, that's easy," the grandmother replied. "This year I didn't sign the checks."